1. Field of the Invention
The present invention relates generally to an illuminated sign and, in particular, to a control circuit for supplying AC and DC power to a plurality of series connected light sources in an sign.
2. Prior Art
Many types of emergency exit signs are shown in the art including those that operate on either AC or DC power. Exit signs of this type frequently require two sets of illuminating lamps, one set for AC operation and a second set for DC operation. Many of the known emergency exit signs use incandescent light bulbs as an illuminating source which use a comparatively high amount of power, thus draining a battery rapidly during DC operation. Also, incandescent light bulbs have a tendency to burn out and must be replaced periodically, adding maintenance costs to the overall cost of the exit sign.
It would be an improvement over the prior art exit signs to provide a single illuminating source for both AC and DC operation which consumes relatively little power and which has a comparatively long life so that it requires infrequent replacement.